package demo1;

import java.util.ArrayList;
import java.util.List;

public class BinaryTree {

    static class TreeNode {
        public char val;
        public TreeNode left;//左孩子的引用
        public TreeNode right;//右孩子的引用

        public TreeNode(char val) {
            this.val = val;
        }
    }


    /**
     * 创建一棵二叉树 返回这棵树的根节点
     *
     * @return
     */

    public TreeNode createTree() {
        TreeNode A = new TreeNode('a');
        TreeNode B = new TreeNode('b');
        TreeNode C = new TreeNode('c');
        TreeNode D = new TreeNode('d');
        TreeNode E = new TreeNode('e');
        TreeNode F = new TreeNode('f');
        TreeNode G = new TreeNode('g');
        A.left = B;
        A.right = C;
        B.left = D;
        B.right = F;
        C.left = E;
        C.right = G;
        return A;
    }

    // 前序遍历
    public void preOrder(TreeNode root) {
        if (root == null) {
            return;
        }
        System.out.print(root.val + " ");
        preOrder(root.left);
        preOrder(root.right);
    }

    // 中序遍历
    void inOrder(TreeNode root) {
        if (root == null) {
            return;
        }
        preOrder(root.left);
        System.out.print(root.val + " ");
        preOrder(root.right);
    }

    // 后序遍历
    void postOrder(TreeNode root) {
        if (root == null) {
            return;
        }
        preOrder(root.left);
        preOrder(root.right);
        System.out.print(root.val + " ");
    }

    public static int nodeSize;

    private void preOrderCoount(TreeNode root) {
        if (root == null) {
            return;
        }
        nodeSize++;
        preOrderCoount(root.left);
        preOrderCoount(root.right);
    }

    /**
     * 获取树中节点的个数：遍历思路
     */
    void size(TreeNode root) {
        preOrderCoount(root);
    }

    /**
     * 获取节点的个数：子问题的思路
     *
     * @param root
     * @return
     */
    int size2(TreeNode root) {
        if (root == null) {
            return 0;
        }
        return size2(root.left) + size2(root.right) + 1;
    }


    /*
     获取叶子节点的个数：遍历思路
     */
    public static int leafSize = 0;

    void getLeafNodeCount1(TreeNode root) {
        if (root == null) {
            return;
        }
        if (root.right == null && root.right == null) {
            leafSize++;
        }
        getLeafNodeCount1(root.left);
        getLeafNodeCount1(root.right);
    }

    /*
     获取叶子节点的个数：子问题
     */
    int getLeafNodeCount2(TreeNode root) {
        if (root == null) {
            return 0;
        }
        if (root.left == null && root.right == null) {
            return 1;
        }
        return getLeafNodeCount2(root.left)
                + getLeafNodeCount2(root.right);
    }

    /*
    获取第K层节点的个数
     */
    int count = 0;

    int getKLevelNodeCount(TreeNode root, int k) {
        if (root == null) {
            return 0;
        }
        if (k == 1) {
            return 1;
        }
        return getKLevelNodeCount(root.left, k - 1) +
                getKLevelNodeCount(root.right, k - 1);
    }

    /*
     获取二叉树的高度
     时间复杂度：O(N)
     */

    int getHeight(TreeNode root) {
        if (root == null) {
            return 0;
        }
        int getLeftCount = getHeight(root.left);
        int getRightCount = getHeight(root.right);
        return getLeftCount > getRightCount ?
                getLeftCount + 1 : getRightCount + 1;
    }

    // 检测值为value的元素是否存在
    public TreeNode find(TreeNode root,char val){
        if(root == null){
            return null;
        }
        if(root.val == val){
            return root;
        }
        TreeNode ret = find(root.left, val);
        if(root.val == val){
            return ret;
        }
        TreeNode ret1  = find(root.right,val);
        if(root.val == val){
            return ret1;
        }
        return null;
    }

        //层序遍历
    void levelOrder (TreeNode root){
        TreeNode tmp = root;
        if(root == null){
            return;
        }
        System.out.println(tmp.val);
        if(root.left != null && root.right != null){
            levelOrder(tmp.left);
            levelOrder(root.right);
            System.out.println(root.val + " ");
        }
    }


    // 判断一棵树是不是完全二叉树
    boolean isCompleteTree (TreeNode root){
        return true;
    }
}